Optical non-invasive blood monitoring system and method

Abstract

A simple noninvasive technique that is capable of very accurate and fast blood analyte, e.g., glucose, level monitoring is provided. Fluctuation in the levels of glucose and other analytes affect the refractive index of blood and extra cellular fluid in biological tissue. Given that the propagation speed of light through a medium depends on its refractive index, continuous monitoring of analyte levels in tissue is achieved by measuring characteristics of the tissue that can be correlated to the refractive index of the tissue. For instance, the frequency or number of optical pulse circulations that are transmitted through an individual's tissue of known thickness within a certain time period can be correlated to an individual's blood glucose level.

1. A device for noninvasive measurement of the levels of at least one analyte in a subject that comprises:
 means for irradiating the subject through tissue with electromagnetic radiation; 
 means for detecting the radiation that passes through the tissue; 
 means for calculating the speed at which the electromagnetic radiation passes through the tissue; 
 means for monitoring at least one of back and forward scattering of electromagnetic radiation within the tissue; and 
 means for correlating the calculated speed of the electromagnetic radiation and the intensity of the at least one of back and forward scattering of the electromagnetic radiation to the concentration of the at least one analyte in the subject. 
 
     
     
       2. The device of  claim 1  comprising means for monitoring attenuation of electromagnetic radiation within the tissue. 
     
     
       3. The device of  claim 1  wherein the means for monitoring at least one of back and forward scattering of the electromagnetic radiation monitors both back and forward scatting of electromagnetic radiation within the tissue. 
     
     
       4. The device of  claim 1  wherein the means for irradiating the subject emits pulses of radiation and the means for detecting the radiation measures the number of pulses of radiation that passes through the tissue during a defined time period which is referred as the pulse circulation frequency measurement. 
     
     
       5. The device of  claim 4  wherein the means for correlating the calculated speed of the electromagnetic radiation and the intensity of the at least one of back and forward scattering of the electromagnetic radiation to the concentration of the at least one analyte in the subject calculates the changes, if any, of the pulse circulation frequency being measured. 
     
     
       6. The device of  claim 1  wherein the means for irradiating the subject emits pulses of radiation and the means for detecting the radiation measures the time period required for a defined number of pulses of radiation to pass through the tissue which is referred to as the time interval measurement. 
     
     
       7. The device of  claim 6  wherein means for correlating the calculated speed of the electromagnetic radiation and the intensity of the at least one back and forward scattering of the electromagnetic radiation to the concentration of the at least one analyte in the subject calculates the changes, if any, of the time interval being measured. 
     
     
       8. The device of  claim 1  further comprising means for dispensing a medical formulation in response to a determination of the concentration of the at least one analyte in the subject. 
     
     
       9. The device of  claim 1  wherein the at least one analyte is selected from the group consisting of glucose, cholesterol, triglycerides, urea, protein, and mixtures thereof. 
     
     
       10. The device of  claim 1  wherein said at least one analyte is glucose. 
     
     
       11. The device of  claim 1  wherein the concentration of two or more analytes are measured and the means for irradiating the subject emits electromagnetic radiation at two or more different wavelengths. 
     
     
       12. The device of  claim 1  wherein the means for irradiating the subject through the tissue with electromagnetic radiation functions at different wavelengths. 
     
     
       13. The device of  claim 1  wherein the means for irradiating the subject comprises means for supporting the device such that the electromagnetic radiation passes through a defined thickness of the tissue. 
     
     
       14. A device for noninvasive measurement of the levels of at least one analyte in a subject that comprises:
 means for irradiating the subject through tissue with electromagnetic radiation at a plurality of different wavelengths; 
 means for detecting the radiation that passes through the tissue; 
 means for calculating the speed at which the electromagnetic radiation passes through the tissue; and 
 means for correlating the calculated speed of the electromagnetic radiation to the concentration of the at least one analyte in the subject, wherein the device employs a single electronic processing unit and wherein the means for calculating and the means for correlating are part of the electronic processing unit. 
 
     
     
       15. The device of  claim 14  wherein the means for irradiating comprises a plurality of optical sources of electromagnetic radiation that irradiates the tissue. 
     
     
       16. The device of  claim 14  wherein the means for detecting comprises a plurality of detectors that detect radiation that is transmitted through the tissue. 
     
     
       17. The device of  claim 14  wherein the electronic processing unit comprises a multiplexer and a demultiplexer. 
     
     
       18. The device of  claim 14  wherein the means for irradiating comprises an optical combiner that combines signals from a plurality of optical sources and wherein the means for detecting comprises an optical splitter that delivers input radiation to a plurality of detectors. 
     
     
       19. The device of  claim 14  wherein the means for irradiating directs electromagnetic radiation with different wavelengths through the subject along different physical paths of different lengths. 
     
     
       20. The device of  claim 14  further comprises means for monitoring at least one of back and forward scattering radiation. 
     
     
       21. The device of  claim 20  wherein the means for monitoring at least one of back and forward scattering radiation monitors both back and forward scattering radiation. 
     
     
       22. A device for noninvasive measurement of the levels of glucose in a subject that comprises:
 means for irradiating the subject through tissue with electromagnetic radiation having a wavelength such that the speed of the electromagnetic radiation propagating through the tissue is sensitive to the glucose concentration in the tissue; 
 means for detecting the radiation that passes through the tissue; 
 means for calculating the speed at which the electromagnetic radiation passes through the tissue; 
 means for monitoring at least one of back and forward scattering of electromagnetic radiation within the tissue; and 
 means for correlating the calculated speed of the electromagnetic radiation and the intensity of the at least one of back and forward scattering of electromagnetic radiation to the concentration of glucose in the subject. 
 
     
     
       23. The device of  claim 22  comprising means for monitoring attenuation of electromagnetic radiation within the tissue. 
     
     
       24. The device of  claim 22  wherein the means for irradiating the subject emits pulses of radiation and the means for detecting the radiation measures the number of pulses of radiation that passes through the tissue during a defined time period, which is referred as the pulse circulation frequency measurement. 
     
     
       25. The device of  claim 24  wherein the means for correlating the calculated speed of the electromagnetic radiation to the concentration of the glucose in the subject calculates the changes, if any, of the pulse circulation frequency being measured. 
     
     
       26. The device of  claim 22  wherein the means for irradiating the subject emits pulses of radiation and the means for detecting the radiation measures the time period required for a defined number of pulses of radiation to pass through the tissue which is referred to as the time interval measurement. 
     
     
       27. The device of  claim 26  wherein the means for correlating the calculated speed of the electromagnetic radiation and the intensity of the at least one of back and forward scattering of electromagnetic radiation to the concentration of the at least one analyte in the subject calculates the changes, if any, of the time interval being measured. 
     
     
       28. The device of  claim 22  further comprising means for dispensing an insulin formulation in response to a determination of the concentration of the glucose in the subject. 
     
     
       29. A device for noninvasive measurement of the levels of glucose in a subject that comprises:
 means for irradiating the subject through tissue with electromagnetic radiation at a plurality of different wavelengths wherein electromagnetic radiation of at least one wavelength is such that the speed of the electromagnetic radiation propagating through the tissue is sensitive to the glucose concentration in the tissue; 
 means for detecting the radiation that passes through the tissue; 
 means for calculating the speed at which the electromagnetic radiation passes through the tissue; and 
 means for correlating the calculated speed of the electromagnetic radiation to the concentration of glucose in the subject, wherein the device employs a single electronic processing unit and wherein the means for calculating and the means for correlating are part of the electronic processing unit. 
 
     
     
       30. The device of  claim 29  wherein the means for irradiating comprises a plurality of optical sources of electromagnetic radiation that irradiates the tissue. 
     
     
       31. The device of  claim 29  wherein the means for detecting comprises a plurality of detectors that detect radiation that is transmitted through the tissue. 
     
     
       32. The device of  claim 29  wherein the electronic processing unit comprises a multiplexer and a demultiplexer. 
     
     
       33. The device of  claim 29  wherein the means for irradiating comprises an optical combiner that combines signals from a plurality of optical sources and wherein the means for detecting comprises an optical splitter that delivers input radiation into a plurality of detectors. 
     
     
       34. The device of  claim 29  wherein the means for irradiating directs electromagnetic radiation with different wavelengths through the subject along different physical paths of different lengths. 
     
     
       35. The device of  claim 29  comprises means for monitoring at least one of forward and back scattering radiation. 
     
     
       36. The device of  claim 35  wherein the means for monitoring at least one of back and forward scattering radiation monitors both back and forward scattering radiation. 
     
     
       37. A noninvasive method of monitoring the levels of at least one analyte in a subject that comprises:
 (a) irradiating the subject through tissue of known thickness with electromagnetic radiation; 
 (b) detecting the radiation that passes through the tissue; 
 (c) calculating the speed at which the electromagnetic radiation passed through the tissue; 
 (d) (i) monitoring attenuation of the radiation that passes through the tissue and/or (ii) monitoring at least one of back and forward scattering of electromagnetic radiation within the tissue; and 
 (e) correlating the calculated speed of the electromagnetic radiation and either the attenuation of the radiation or the intensity of the at least one of back and forward scattering or both the attenuation of the radiation and the intensity of the at least one back and forward scattering to the concentration of the at least one analyte in the subject. 
 
     
     
       38. The method of  claim 37  wherein step (d) comprises monitoring attenuation of the radiation that passes through the tissue. 
     
     
       39. The method of  claim 37  wherein step (d) comprises monitoring at least one of back and forward scattering of electromagnetic radiation within the tissue. 
     
     
       40. The method of  claim 37  wherein step (d) comprises monitoring both back and forward scattering of electromagnetic radiation within the tissue. 
     
     
       41. The method of  claim 37  wherein step (a) comprises directing pulses of radiation through the tissue and step (b) comprises detecting the number of pulses that passes through the tissue during a defined time period, which is referred as the pulse circulation frequency measurement. 
     
     
       42. The method of  claim 41  wherein step (d) comprises calculating the changes, if any, of the pulse circulation frequency being measured. 
     
     
       43. The method of  claim 37  wherein step (a) comprises directing pulses of radiation and step (b) comprises measuring the time period required for a defined number of pulses of radiation to pass through the tissue which is referred to as the time interval measurement. 
     
     
       44. The method of  claim 43  wherein step (d) comprise calculating the changes, if any, of the time interval being measured. 
     
     
       45. The method of  claim 37  further comprising the step of dispensing a medical formulation in response to a determination of the concentration of the at least one analyte in the subject. 
     
     
       46. The method of  claim 37  wherein the at least one analyte is selected from the group consisting of glucose, cholesterol, triglycerides, urea, protein, and mixtures thereof. 
     
     
       47. The method of  claim 37  wherein said at least one analyte is glucose. 
     
     
       48. The method of  claim 37  wherein the concentration of two or more analytes are measured and step (a) comprises irradiating the subject with electromagnetic radiation at two or more different wavelengths. 
     
     
       49. The method of  claim 37  wherein step (a) comprises irradiating the subject through tissue with electromagnetic radiation at different wavelengths.